Assuming a novel model based on a minimal cartography where every syntacticnode in the structure encodes semantic information (see Romeu, 2014), inthis paper I argue that the difference between ser and estar in Spanish is due tothe presence of two different modifiers (Conjoint and Disjoint) of the node Stat(which introduces a state) in their respective underlying structures, similarly to theway that the prepositions a and en are distinguished in Romeu (2014). Althoughboth ser and estar lexicalize Stat, ser can also lexicalize Conjoint, which gives theinterpretation that there is only one state in the situation described, and estaralso lexicalizes Disjoint, which gives the interpretation that the state encoded byStat is linked to a different state and that there exists a link or relation betweenthese two states. This contrast accounts for the different properties of ser andestar that have been pointed out in the literature: individual-level/stage-levelopposition, permanent/temporary interpretation, scalar interpretation of estar,evidential use of estar, etc.